The concept of collapsible containers held in rigid containers has been practiced for many years. These concepts can range from the relatively simple such as, a cardboard coffee tote with a flexible plastic bladder, to more complex systems for handling hazardous or highly pure chemicals in specialized double-wall sealed containers. Regardless of design, the general principle involves a flexible container in the shape of a pouch or bag that collapses as the contents of the bag or pouch are extracted or dispensed. The flexible container is contained in a rigid outer container such as a box, drum, or bottle used to support and protect the flexible pouch or bag and to provide containment for a pressurization fluid used to collapse the bag or pouch.
A variety of improved collapsible container designs have been suggested and patented. Examples of collapsible bag-in-container designs include U.S. Pat. No. 3,223,289 to Bouet, U.S. Pat. No. 5,377,876 to Smernoff, and U.S. Pat. No. 5,562,227 to Takezawa et al., each of which is hereby incorporated by reference herein except for explicit definitions contained therein. A variety of bag-in-bottle designs have also been contemplated in the design of chemical containers. Representative examples include U.S. Pat. No. 4,793,491 to Wolf et al., U.S. Pat. No. 5,102,010 to Osgar et al., U.S. Pat. No. 5,597,085 to Rauworth et al., and U.S. Pat. No. 6,158,853 to Olsen et al., each of which is hereby incorporated by reference herein except for explicit definitions contained therein.
Additionally, a variety of alternative designs utilizing one or more methods of extracting the contents of the flexible bag from the container assembly have been utilized. Examples of these designs include U.S. Pat. No. 3,467,283 to Kinnavy, U.S. Pat. No. 3,767,078 to Gortz et al., U.S. Pat. No. 4,445,539 to Credle, U.S. Pat. No. 4,925,138 to Rawlins, U.S. Pat. No. 6,206,240 to Osgar et al., U.S. Pat. No. 6,345,739 to Mekata, U.S. Pat. No. 6,698,619 to Wertenberger, and U.S. Pat. No. 6,942,123 to Wertenberger, each of which is hereby incorporated by reference herein except for explicit definitions contained therein. These configurations have not provided optimal performance and cleanliness particularly for dispensing highly pure fluids in the semiconductor processing industry, for example, photoresist. Typically, the pressurization fluid is provided to the space between an inner dispense bag and a rigid outer container. In such an arrangement, the inner bag may collapse non-uniformly causing an excess amount of the fluid to remain in the inner bag, preventing the complete dispensing of the fluid. The wasted fluid also exacerbates recycling and disposal issues associated with the inner bag.
Bag-in-bottle dispensers are used extensively in the photolithography industry for dispensing photoresist. It has been discovered that where the pressurization fluid is a gas (e.g., nitrogen), the gas can permeate the walls of the flexible containers comprised of materials (e.g. fluoropolymers) that are compatible with dispense photoresist. Accordingly, in systems where the pressurization fluid is in direct contact with the flexible container holding the dispense liquid, the pressurization gas can diffuse into the flexible container, thereby causing micro-bubbles to form within the contained dispense fluid and contaminating the dispense fluid.
Fluoropolymer-based materials are difficult to bond with materials that are highly gas impermeable (e.g., polyethylene), due in part to substantially different melt temperatures of the respective materials. Recent efforts addressing the gas diffusion issue have included abandonment of fluoropolymer-based materials and providing a single flexible bag with a dual wall, wherein the inner wall is a clean polyethylene and the outer wall is a polyethylene/nylon laminate that resists gas permeation. The polyethylene-based materials were chosen for compatibility in the bonding process of the inner wall to the outer wall. It was found, however, that the resistance of the inner wall to photoresist was inadequate.
There remains a need to identify improved designs that have a minimum of cost and contamination while maximizing device integrity, flexibility of use, and ease of predictably extracting the contents of the container.